#求排列数
def A(n,m):
    AP = n
    for i in range(1,m):
        AP *= (n-i)
    return AP

#求组合数
def C(n,m):
    CZ = n
    for i in range(m-1):
        CZ *= (n-i-1)/(m-i)
    return round(CZ)

